Biocrust belt below the edge of a dying glacier in the Tropical Andes

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Gutiérrez-Lagoueyte, Ingibjörg S. Jónsdóttir, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9044279/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract Life can be unstable. This is especially true for seedlings growing on erodible surfaces, such as newly exposed areas after glacier retreat. Here we used a space-for-time approach to study the role of biological soil crust (biocrust) as surface stabilizer and facilitator of ecological succession along a glacier forefield chronosequence at the retreating Conejeras glacier in the Tropical Andes. We used the point-intercept method to estimate surface cover of plants, biocrust, bare ground and rocks, as well as surface roughness; and a field soil aggregate kit to estimate soil stability. As hypothesized, following a bare-ground stage near the edge of the glacier, the successional trajectory involved the development of a biocrust belt, including bryophytes and lichens, followed by an increasing vascular plant cover in more advanced successional stages. The development of biocrust was accompanied by higher roughness and stability, which likely increased seed entrapment and seedling establishment. Our results suggest that the development of cyanobacterial-dominated biocrust at the forefield of the Conejeras glacier may favor the establishment of plants with large seeds, such as graminoids from the Festuca genus. Overall, our findings highlight the key role of biocrusts in the ecological dynamics that follow glacier melt in the Tropical Andes. Biological soil crust (biocrust) vascular plants páramo ecological succession glacier chronosequence climate change Figures Figure 1 Figure 2 Figure 3 Introduction In the high-elevation Tropical Andes, where glaciers are melting at a fast pace (Rabatel et al., 2018 ; Ruiz et al., 2008 ; Ceballos et al., 2006 , 2024), plant species of the páramo and super-páramo may be in a climate-driven race to higher elevations (Anthelme et al., 2022 ; Cuesta et al., 2023 ; but see Chen et al., 2025 ). The success of their climbing depends on the dispersal and survival of reproductive organs, such as seeds (Tovar et al., 2020 ). One of the key factors determining seedling survival and further plant development, particularly in these steep, erodible surfaces, is soil stability (Espigares et al., 2011 ), which can be enhanced by the development of biological soil crust, also referred to as biocrust (Belnap and Büdel, 2016 ; Hu et al., 2002 ). Biocrusts are composed of soil particles held together by organisms such as cyanobacteria, lichen and bryophytes (Weber et al., 2022). Partly for this reason, surfaces covered with biocrusts are much more resistant to wind and water erosion than bare ground, where biocrust has been removed or has not yet developed (Belnap et al., 2014 ; Chamizo et al., 2017). Also, the formation of biocrust can increase surface roughness (Rodríguez-Caballero et al., 2012 ), which in turn can increase seed entrapment (Elmarsdottir et al., 2003 ), especially in areas vulnerable to erosion, such as the forefield of a melting glacier. Furthermore, biocrusts can fix C and N (Elbert et al., 2012 ; Rodriguez-Caballero et al., 2018; Reis et al., 2025), and reduce hydrological stress by increasing moisture retention during dry periods (Eldridge et al., 2020). Because of this, biocrusts often serve as safe sites for seedling establishment and growth (Behrend et al., 2025 ; Aradottir and Halldorsson, 2018 ; Tavili et al., 2017 ). However, depending on site-specific conditions, seed features, and intrinsic properties of biocrust types, biocrusts can also have a negative or neutral effect on seedling development (Bacovcin et al., 2025 ; Havrilla et al., 2019 ). Most of the scientific literature on biocrust comes from warm arid or semi-arid ecosystems (Weber et al., 2022). However, biocrusts are widespread in cold and mesic environments too, including at high-latitudes (Salazar et al., 2025; Pushkareva et al., 2016 ), and at high-elevation tropical ecosystems (Anthelme et al., 2022 ; Llambí et al., 2021 ; Schmidt et al., 2008 ). With ongoing climate change, biocrust cover is projected to decrease under all Representative Concentration Pathways (RCPs) in warm drylands (Rodriguez-Caballero et al., 2018). In contrast, in cold and mesic environments, biocrust cover may increase (Salazar et al., 2025; Mallen-Cooper et al., 2023 ), including in newly exposed areas after the melting of glaciers (Tanner, 2025 ; Schmidt et al., 2008 and 2025 ; Yoshitake et al., 2018 ; Breen and Lévesque, 2008). In these environments, biocrust-forming organisms are among the first colonizers and the development of biocrusts may play a key role in primary succession, by determining surface stability and whether and which plant species establish; as well as when, and how fast they grow, thus influencing the successional trajectory. To deepen our understanding of the role biocrusts play in primary succession within glacial environments, we used a space-for-time approach to examine a well-defined chronosequence along the forefield of the Conejeras glacier, at the Santa Isabel Nevado —one of the glaciers with the highest area loss rate per year in Colombia (Rabatel et al., 2018 , Ceballos et al., 2024). Most research at this glacial forefield has focused on the monitoring of ice mass and cover (e.g., Ruiz-Carrascal et al., 2022 ; Rabatel et al., 2018 ; Ceballos et al., 2006 ; Poveda and Pineda, 2009 ) and on the composition (Anthelme et al., 2022 ) and activity (Meyers et al., 2023 ) of plant communities. Here, we aimed at contributing to this research by investigating the potential role of biocrust in primary succession through surface colonization, soil surface stabilization and plant establishment facilitation. According to succession theory, we expected to find changes in biocrust and vegetation development from recently deglaciated areas closer to the edge of the glacier, to areas farther away where the glacier retreated longer ago. We hypothesized that biocrust cover would be highest near the glacier edge and decrease at lower elevations, where vascular plants have had more time to establish and expand. Overall, we expect this research to shed light on the role of biocrusts as potential key regulators of ecological succession as Tropical glaciers in the Andes and in comparable ecosystems melt. Methods and materials Study site We tested our hypotheses at a glacier forefield chronosequence (Fig. 1 A) set by Anthelme et al. ( 2022 ), near the edge of the glacier Conejeras, Nevado Santa Isabel, Colombia (4° 49′ 12.9324'' N 75° 22′ 33.2112'' W). The chronosequence is located between ca. 4350 and 4700 m.a.s.l. The mean (2013–2017) annual temperature and precipitation at the edge of the glacier are 1.3°C and 1025 mm, respectively (Anthelme et al., 2022 ; Morán-Tejeda et al., 2018 ). The National Natural Parks of Colombia (PNN, after its Spanish abbreviation) and the Institute of Hydrology, Meteorology and Environmental Studies (IDEAM, after its Spanish abbreviation) marked the edge of the glacier in 2020, 2010, 1990, 1960 and ca. 1850 along an elevational gradient (Fig. 1 A, B). These locations represent a chronosequence of glacier retreat where we conducted our field survey on June 17th, 2025. At each of these locations, we established a 60-m horizontal transect, positioned ca. 5 m downhill approximately along the contour line (Fig. 1 C) where we measured surface cover, roughness, and stability. At the lowest sampling location, corresponding to the location of the glacier edge in ca. 1850, the PNN sign is placed on the glacier’s moraine. Since our goal was to study the soil and plant communities after the glacier retreat, in this case, we located the transect ca. 50 m uphill, beyond an area disturbed by the construction of a wooden trail (Figure S1 ,H). Surface cover, roughness and stability At each of the sampling locations we measured surface cover in three 50 x 50 cm 2 , evenly distributed along the horizontal transect using the point-intercept method (Fig. 2 A,C). We used a light point-intercept device with a single row of points along a 50 cm long stick (Fig. 2 A), and recorded surface cover in a grid with nine evenly distributed points by moving the instrument twice (Fig. 2 C). In each point, we recorded bare-ground (Figure S1 ,A) and rocks (Figure S1 ,B), as well as the occurrence of biocrusts dominated by cyanobacteria (Figure S1 ,C), lichens (Figure S1 ,D) or bryophytes (Figure S1 ,E), and non-crusted lichens (Figure S1 ,F), non-crusted-bryophytes (Figure S1 , G) and vascular plants (Figure S1 ,H). When bryophytes and lichens were not part of a crusted system, but rather formed a carpet or a foliose structure (Figure S1 ,F and G), they were recorded as such. Since. When the same species was hit (intercepted) multiple times in the same point, we recorded it (Table S7) but only used the first hit to calculate cover. At the same time, we measured surface roughness similar to Mallen-Cooper et al. ( 2020 ; Fig. 2 A,C). Specifically, in 9 points at 5 cm intervals along the uppermost row of the plot grid we recorded the distance between the top of the pin and the horizontal bar of the point-intercept device (9 points in total; Fig. 2 C), and estimated surface roughness based on the standard deviation (SD) of the pin heights. Since we measured roughness along contour lines, slope did not have a major influence on the measurements (e.g., Fig. 2 A) and therefore we did not remove it before calculating SDs. Finally, we measured surface (1–2 cm) stability with a Jornada Experimental Range Soil Stability Test Kit (Fig. 2 B,C), as described by Herrick et al. ( 2001 ). For the latter, we took three samples per quadrat, along the uppermost row for the point intercept analysis (Fig. 2 C). From field measurements, we calculated the percentage cover of five different cover types: biocrust, bryophytes, lichens, vascular plants, and bare ground and rocks (Figure S1 ) as follows: $$Cover\left(\%\right)=\left(\frac{Numberofhitsforacovertype}{Totalnumberofpointsingrid}\right)\times100$$ Where the total number of points in a grid was 9 (Fig. 2 C). Statistical analysis We used linear mixed effects models (LMMs) to analyze surface roughness, stability and cover along the glacier forefield chronosequence. In the case of surface cover, in which we used one LMM per cover type, the models included the fixed effects of elevation and the random effects of the location of the grids within transects. Since we hypothesized a non-linear change of biocrust cover along the chronosequence, with biocrust cover peaking at high but not the highest elevation where glacial retreat is most recent and biocrust has not had time to develop, we included a quadratic term for elevation in the LMMs. We used the Akaike Information Criterion (AIC) to compare the performance of the models with and without the quadratic term. Considering the focus of our hypothesis, as well as the relatively small size of our dataset, we grouped the cover data into five categories: vascular plants, non-biocrust bryophytes, non-biocrust lichens, biocrust, and rocks and bare ground. However, when possible, we recorded and analyzed surface cover in more detail, for example, in the case of biocrusts with different dominant components: cyanobacteria, lichens or liverworts. To be able to compare potential non-linear behaviors of surface roughness and stability, related to biocrust cover, we also included a quadratic term for elevation (or site age) in the roughness and stability LMMs. We considered each of the three grids in the 60 m transects (one per elevation level) as replicates (N = 3). We used R (R core team, 2025 ), version 4.5.2, for all statistical analyses and. For the LMMs, we used the lme4 (Bates et al., 2015 ) and lmerTest (Kuznetsova et al., 2017 ) packages. Results and discussion Our findings highlight two major successional events along the glacier forefield chronosequence at Conejeras: a primary succession characterized by bryophyte growth and the development of biocrust, as well as by an increase in surface roughness and stability, at a high but not the highest elevation near the edge of the glacier; followed by an increase in the cover of vascular plants that replaced biocrust and bare ground, at lower elevations (Fig. 3 ; Tables S2-6). Our space-for-time substitution approach suggests that biocrust, followed by bryophytes and lichens, became the dominant biological feature of the soil surface 15 year after the retreat of the glacier (4690 m.a.s.l.). Biocrust cover reached a maximum of ca. 50% of the total surface after 35 yrs (4660 m.a.s.l.), and remained a main feature of the surface after 65 yrs (4648 m.a.s.l.; Fig. 3 A, Table S3) —the hypothesized biocrust belt. Beyond this location, at lower elevations, biocrust cover decreased and vascular plant cover increased, which together with findings discussed below, suggests a facilitating effect of biocrust on vascular plant establishment during primary succession in alpine environments or similar. The estimated time needed for biocrust development on bare surfaces at the Conejeras area is comparable to those observed in other glacier forefield chronosequences, both in alpine environments in the Tropical Andes (Llambi et al., 2021) and in glacial forefields at high latitudes (Tanner, 2025 ; Yoshitake et al., 2018 ; Breen and Lévesque, 2008). Also, the higher abundance of cyanobacteria-dominated biocrust on the highest and youngest stages of the chronosequence, compared to the more lichen- and bryophyte-dominated biocrusts in the lower parts (Table S7), follows the expected succession within the biocrust communities (Maier et al., 2018 ; but see Kidron and Xiao, 2024 ). However, the role of biocrust in ecological succession after the melting of glaciers can vary between sites depending on abiotic conditions and intrinsic biocrust-vegetation relationships. In a similar study at the North-West flank of the glacier forefront at Humboldt peak, in the Sierra Nevada National Park, Venezuela, biocrust covered almost 80% of the surface 10 yrs after the edge of the glacier retreated (Llambi et al., 2021). At lower sites, corresponding to the locations of the edge of the glacier up to 109 yrs after it retreated, biocrust cover decreased as in our study, but still remained the dominant feature of the ecosystem, covering 50–60% of the total surface (Llambi et al., 2021). This suggests that either abiotic components such as climate were halting ecological succession, or that biocrusts acted as a barrier for the establishment of vascular plants (e.g., as in Gilbert and Corbin, 2019 ). Lichen-dominated biocrusts, which are widespread at the glacier forefront at Humboldt peak (Llambi et al., 2021), often have neutral or negative effects on seedling emergence (Bacovcin et al., 2025 ; Havrilla et al., 2019 ). In contrast, cyanobacteria-dominated biocrust, characterized by dark pigmentation (Figs. 2 A and S1,B), and which was the most abundant biocrust type at the biocrust belt in our site (Table S7), often facilitates seedling emergence (Bacovcin et al., 2025 ; but see Havrilla et al. 2019 ), especially of medium-size (0.51-1 g/1000 seeds) and large (1.1 + g/1000 seeds) seeds (Bacovcin et al., 2025 ). The most abundant (0–15% cover) vascular plant growth form at the biocrust belt at the Conejeras glacier were graminoids, such as those of the Festuca genus (Table S7; see also Figs. 2 A), followed by the dwarf evergreen shrub Gaultheria myrsinoides (Table S7). Festuca seeds, which generally weigh more than 1g/1000 seeds (López et al., 2021 ; Fairey and Lefkovitch, 1996 ), are approximately one order of magnitude heavier than those of Gaultheria myrsinoides (Romero-Saritama et al., 2020). The positive effect of cyanobacteria-dominated biocrust on large seed establishment —i.e., its role as a biological filer influencing plant species composition—, could partially explain why graminoids were the dominant vascular plant in the biocrust belt on the glacier forefield chronosequence at the Conejeras glacier, and shed light on possible trajectories of ecological succession in Tropical páramos and superpáramos, as glaciers continue melting. At a comparable glacier forefield chronosequence in southern Iceland, biocrust covered ca. 25% of a moraine surface ca. 20 yrs after being exposed by glacier retreat (Tanner, 2025 ). As in our study site, biocrust cover decreased along the chronosequence, down to ca. 5% in areas corresponding to the location of the edge of the glacier in 1965 and 1954. However, contrary to the expected trend according to successional theory, biocrust cover increased again to ca 25% in the area corresponding to the glacier edge in 1946, and decreased as expected afterwards. In this case, biocrust cover seems to have been influenced by topography and climate as well: the two areas with the highest biocrust cover in the glacier forefield chronosequence in southern Iceland were those topographically lowest and most sheltered (Tanner, 2025 ). At the forefield chronosequence of the Conejeras glacier, the decrease in biocrust cover at 4648 m.a.s.l., immediately below the area with a maximum biocrust cover of ca. 50%, was partly due to the presence of large rocks (Figs. 3 A and S1,E). Together, our results and related research highlight the key role of biocrusts in primary succession in newly exposed areas after glacier melting, and show how biocrust-vegetation relationships can be affected by abiotic factors such as climate and geomorphological formations. From a mechanistic perspective, our results of soil roughness and stability increasing with biocrust cover (Fig. 3 ; Tables S8 and 9) contribute to the body of research highlighting these two as key processes through which biocrusts influence seed trapping, seedling establishment, and ultimately primary ecological succession (Chamizo et al., 2017; Belnap and Büdel, 2016 ; Rodríguez-Caballero et al., 2012 ; Elmarsdottir et al., 2003 ). The statistical significance of the non-linear change of soil roughness with elevation was marginal (Table S8). This could reflect that roughness was not only affected by the presence or absence of biocrust, which also had a marginal, non-linear behavior with elevation (Table S3), but also by other features of the ecosystem such as vegetation and rocks. Moreover, it could indicate that at Conejeras, biocrusts play a larger role in ecological succession via increases in soil stability, which had a strong non-linear response to elevation (Table S9). Despite the weak statistical significance of the non-linear variation of surface roughness with elevation, the largest relative increase in roughness along the chronosequence was between the highest-elevation site dominated by bare ground and the next lower elevation site, where the dominant biological features were bryophytes and biocrust. Rougher surfaces reduce overland flow speed, which can promote microdepressions and indirectly affect sediment loss and successional dynamics (Rodríguez-Caballero et al., 2012 ). Overall, our findings and numerous observations of biocrust increasing surface roughness (Ji et al., 2025; Caster et al., 2021 ; Rodríguez-Caballero et al., 2012 ), suggest that at the Conejeras site, roughness may play an important role in seed entrapment and eventual seedling establishment. Soil stability was lowest at the highest elevation, entirely covered by bare ground and rocks (Figure S1 ,A), then it substantially increased at lower elevations, peaking at the area primarily covered by biocrust (4,660 m), and remained high at the lowest points where biocrusts are replaced by vascular plants (Fig. 3 A,C; Table S9). Our finding is similar to one at the Piedras Blancas páramo in Venezuela, where the formation of biocrust increased surface resistance to raindrop erosion by ca. 5 times compared to non-crusted soil (Pérez, 1997). The positive effect of biocrust formation on soil stability may be more consequential for seedling establishment in steep glacier forefields prone to runoff erosion, like at Conejeras and similar alpine environments, than in less steep ones. In addition to soil stability, there are other factors that can affect seedling performance and that were not included in our analysis, such as nitrogen fixation (Salazar et al., 2022) or water regulation (Eldridge et al., 2020). It remains to be understood to what extent these mechanisms play a role in the ongoing ecological succession at the Conejeras area and similar glacier forefields. Finally, not all bryophytes and lichens along the Conejeras chronosequence were part of a biocrust community. Some bryophytes formed non-crusted structures such as mats or cushions (Figure S1 ,G; Table S7), and likewise, some lichens formed lichen-only crustose or foliose structures (Figure S1 ,F; Table S7). Non-crusted bryophytes can increase seed entrapment too (Linskens et al., 1993 ). However, they seem to facilitate seedling establishment only when the bryophyte is very small (e.g., 1 cm or less; Behrend et al., 2025 ), which in many cases may mean that it is part of a biocrust community. When the bryophyte is taller, seeds can be trapped, but they do not reach the ground and therefore do not develop (Behrend et al., 2025 ). Lichens can increase seedling recruitment too (Nystuen et al., 2019 ). However, when they become dominant, they often act like a shield or hardened barrier that prevents the establishment of vascular plants (Bacovcin et al., 2025 ; Havrilla et al., 2019 ). Immediately below the highest and youngest stages of the Conejeras chronosequence, biocrust cover was higher than that of non-crusted bryophytes and lichens. On the other hand, at the lower and oldest sites, the cover of non-crusted bryophytes and lichens was 20–30%, whereas that of biocrust was ca. 0% (Fig. 2 A). This could be an indicator of a more effective primary colonization of newly exposed soil by biocrust than by individual bryophytes and lichens, as well as more growth of vascular plants on biocrust than on bryophyte- and lichen-only structures. Conclusions Biocrust development on the highest and youngest stages of the Conejeras chronosequence increases the roughness and stability of the soil surface, which can facilitate the establishment of vascular plants, especially those with large seeds. Our space-for-time analysis indicates that biocrust development starts a few years after the glacier retreats, and together with bryophytes and lichens becomes the dominant feature of the surface. In this elevational range, which in our study covered the area corresponding to 15–65 yrs after the melting of the glacier (4648–4660 m.a.s.l.) —the biocrust belt—, biocrusts play a key role in the functioning of the ecosystem, including in the roughness and stability of the surface, and therefore indirectly on hydrological dynamics, nutrient cycling and ecological succession. Overall, our findings represent one additional piece of evidence and perspective to understand the key role of biocrust on primary succession and the ecological dynamics that follow the rapid melting of glaciers in the Tropical Andes. Declarations Acknowledgments This research was conducted during the summer course Tundra meets the páramo , organized by the Agricultural University of Iceland (AUI) in collaboration with Del Rosario University and EIA University, Colombia; and the University of Iceland and University of Akureyri, Iceland. We thank all the people involved in the preparation of this course and research, and the local collaborators, especially the PNN, including the park ranger Alfredo Bañol, who helped with the collection of soil stability data. Also, we thank Þórey B. Björnsdóttir for her help in collecting point-intercept data. ERC is supported by the Ramon y Cajal fellowship (RYC2020-030762-I) and projects SOLARID2Envi (reference PID2024–161692OB-C31) and CNS2024-154916 funded by MICIU/AEI /10.13039/501100011033 and UE NextGenerationEU/PRTR. This research involves a collaboration of the AUI and the University of Almería, two partners of the UNIgreen alliance. References Anthelme F, Carrasquer I, Ceballos JL, Peyre G (2022) Novel plant communities after glacial retreat in Colombia:(many) losses and (few) gains. Alp Bot 132(2):211–222. https://doi.org/10.1007/s00035-022-00282-1 Aradottir AL, Halldorsson G (2018) Colonization of woodland species during restoration: seed or safe site limitation? Restor Ecol 26:S73–S83. https://doi.org/10.1111/rec.12645 Bacovcin J, McIntyre C, Havrilla CA (2025) Morphological Seed Traits Structure Relationships Between Biocrusts and Plant Emergence. Ecol Evol 15(6):e71450. https://doi.org/10.1002/ece3.71450 Bates D, Mächler M, Bolker B, Walker S (2015) Fitting linear mixed-effects models using lme4. J Stat Softw 67:1–48. http://doi.org/10.18637/jss.v067.i01 Behrend AM, Aradóttir ÁL, Svavarsdóttir K, Thórhallsdóttir TE, Pommerening A (2025) Natural colonization as a means to upscale restoration of subarctic woodlands in Iceland. Restor Ecol 33(1):e14332. https://doi.org/10.1111/rec.14332 Belnap J, Büdel B (2016) Biological soil crusts as soil stabilizers. Biological soil crusts: an organizing principle in drylands. Springer International Publishing, Cham, pp 305–320. https://doi.org/10.1007/978-3-319-30214-0_16 Belnap J, Walker BJ, Munson SM, Gill RA (2014) Controls on sediment production in two US deserts. Aeolian Res 14:15–24. https://doi.org/10.1016/j.aeolia.2014.03.007 Breen K, Lévesque E, Arctic (2008) Antarct Alp Res, 40(2), 287–297. https://doi.org/10.1657/1523-0430(06-098)[BREEN]2.0.CO;2 Caster J, Sankey TT, Sankey JB, Bowker MA, Buscombe D, Duniway MC, Joyal T (2021) Biocrust and the soil surface: Influence of climate, disturbance, and biocrust recovery on soil surface roughness. Geoderma 403:115369. https://doi.org/10.1016/j.geoderma.2021.115369 Ceballos Liévano JL, Mendoza C, Martínez AF, Serrano S y, Zuluaga Cárdenas LC (2024) Informe del estado de los glaciares colombianos 2023. Instituto de Hidrología, Meteorología y Estudios Ambientales - Ideam. ISSN: 2806 – 0261. http://archivo.ideam.gov.co/web/ecosistemas/investigacion-publicaciones . Accessed on 18/12/2025 Ceballos JL, Euscátegui C, Ramírez J, Cañon M, Huggel C, Haeberli W, Machguth H (2006) Fast shrinkage of tropical glaciers in Colombia. Ann Glaciol 43:194–201. https://doi.org/10.3189/172756406781812429 Chen YH, Lenoir J, Chen IC (2025) Limited evidence for range shift–driven extinction in mountain biota. Science 388(6748):741–747. http://doi.org/10.1126/science.adq9512 Corbin JD, Thiet RK (2020) Temperate biocrusts: mesic counterparts to their better-known dryland cousins. Front Ecol Environ 18(8):456–464. https://doi.org/10.1002/fee.2234 Cuesta F, Carilla J, LLambí LD, Muriel P, Lencinas MV, Meneses RI, Tovar C (2023) Compositional shifts of alpine plant communities across the high Andes. Glob Ecol Biogeogr 32(9):1591–1606. https://doi.org/10.1111/geb.13721 Elbert W, Weber B, Burrows S, Steinkamp J, Büdel B, Andreae MO, Pöschl U (2012) Contribution of cryptogamic covers to the global cycles of carbon and nitrogen. Nat Geosci 5:459–462. https://doi.org/10.1038/ngeo1486 Elmarsdottir A, Aradottir AL, Trlica MJ (2003) Microsite availability and establishment of native species on degraded and reclaimed sites. J Appl Ecol 40(5):815–823. https://doi.org/10.1046/j.1365-2664.2003.00848.x Espigares T, Moreno-de las Heras M, Nicolau JM (2011) Performance of vegetation in reclaimed slopes affected by soil erosion. Restor Ecol 19(1):35–44. https://doi.org/10.1111/j.1526-100X.2009.00546.x Fairey NA, Lefkovitch LP (1996) Ploidy and cultivar group differences in the thousand-seed weight of red fescue (Festuca rubra L). Can J Plant Sci 76(3):465–467. https://doi.org/10.4141/cjps96-082 Gilbert JA, Corbin JD (2019) Biological soil crusts inhibit seed germination in a temperate pine barren ecosystem. PLoS ONE 14(2):e0212466. https://doi.org/10.1371/journal.pone.0212466 Kidron GJ, Xiao B (2024) A false paradigm? Do biocrust types necessarily reflect ‘successional stages’? Ecohydrology 17(1):e2610. https://doi.org/10.1002/eco.2610 Kuznetsova A, Brockhoff PB, Christensen RH (2017) lmerTest package: tests in linear mixed effects models. J Stat Softw 82:1–26. http://doi.org/10.18637/jss.v082.i13 Havrilla CA, Chaudhary VB, Ferrenberg S, Antoninka AJ, Belnap J, Bowker MA, Barger NN (2019) Towards a predictive framework for biocrust mediation of plant performance: a meta-analysis. J Ecol 107(6):2789–2807. https://doi.org/10.1111/1365-2745.13269 Herrick JE, Whitford WG, De Soyza AG, Van Zee JW, Havstad KM, Seybold CA, Walton M (2001) Field soil aggregate stability kit for soil quality and rangeland health evaluations. CATENA 44(1):27–35 Hu C, Liu Y, Song L, Zhang D (2002) Effect of desert soil algae on the stabilization of fine sands. J Appl Phycol 14(4):281–292. https://doi.org/10.1016/S0341-8162(00)00173-9 Laureen Drahorad S, Felix-Henningsen P (2012) An electronic micropenetrometer (EMP) for field measurements of biological soil crust stability. J Plant Nutr Soil Sci 175(4):519–520. https://doi.org/10.1002/jpln.201200026 Linskens HF, Bargagli R, Cresti M, Focardi S (1993) Entrapment of long-distance transported pollen grains by various moss species in coastal Victoria Land. Antarctica Polar Biology 13(2):81–87. https://doi.org/10.1007/BF00238539 Llambí LD, Melfo A, Gámez LE, Pelayo RC, Cárdenas M, Rojas C, Hernández J (2021) Vegetation assembly, adaptive strategies and positive interactions during primary succession in the forefield of the last Venezuelan glacier. Front Ecol Evol 9:657755. https://doi.org/10.3389/fevo.2021.657755 López AS, López DR, Arana MV, Batlla D, Marchelli P (2021) Germination response to water availability in populations of Festuca pallescens along a Patagonian rainfall gradient based on hydrotime model parameters. Sci Rep 11(1):10653. https://doi.org/10.1038/s41598-021-89901-1 Maier S, Tamm A, Wu D, Caesar J, Grube M, Weber B (2018) Photoautotrophic organisms control microbial abundance, diversity, and physiology in different types of biological soil crusts. ISME J 12(4):1032–1046. https://doi.org/10.1038/s41396-018-0062-8 Mallen-Cooper M, Bowker MA, Antoninka AJ, Eldridge DJ (2020) A practical guide to measuring functional indicators and traits in biocrusts. Restor Ecol 28:S56–S66. https://doi.org/10.1111/rec.12974 Mallen-Cooper M, Rodríguez‐Caballero E, Eldridge DJ, Weber B, Büdel B, Höhne H, Cornwell WK (2023) Towards an understanding of future range shifts in lichens and mosses under climate change. J Biogeogr 50(2):406–417. https://doi.org/10.1111/jbi.14542 Meyers B, Gutiérrez-Lagoueyte ME, Tobon C (2023) Measurement of actual evapotranspiration in a páramo ecosystem using portable closed chambers: Comparison between giant rosettes, tussock grasses and shrubs. Ecohydrology 16(4):e2525. https://doi.org/10.1002/eco.2525 Morán-Tejeda E, Ceballos JL, Peña K, Lorenzo-Lacruz J, López-Moreno JI (2018) Hydrol Earth Syst Sci 22(10):5445–5461. https://doi.org/10.5194/hess-22-5445-2018 . Recent evolution and associated hydrological dynamics of a vanishing tropical Andean glacier: Glaciar de Conejeras, Colombia Nystuen KO, Sundsdal K, Opedal ØH, Holien H, Strimbeck GR, Graae BJ (2019) Lichens facilitate seedling recruitment in alpine heath. J Veg Sci 30(5):868–880. https://doi.org/10.1111/jvs.12773 Poveda G, Pineda K (2009) Reassessment of Colombia's tropical glaciers retreat rates: are they bound to disappear during the 2010–2020 decade? Advances in Geosciences. 22:107–116. https://doi.org/10.5194/adgeo-22-107-2009 Pushkareva E, Johansen JR, Elster J (2016) A review of the ecology, ecophysiology and biodiversity of microalgae in Arctic soil crusts. Polar Biol 39(12):2227–2240. https://doi.org/10.1007/s00300-016-1902-5 R Core Team (2025) R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria. < https://www.R-project.org/ Rabatel A, Ceballos JL, Micheletti N, Jordan E, Braitmeier M, González J, Zemp M (2018) Toward an imminent extinction of Colombian glaciers? Geogr Annaler: Ser Phys Geogr 100(1):75–95. https://doi.org/10.1080/04353676.2017.1383015 Rodríguez-Caballero E, Cantón Y, Chamizo S, Afana A, Solé-Benet A (2012) Effects of biological soil crusts on surface roughness and implications for runoff and erosion. Geomorphology 145:81–89. https://doi.org/10.1016/j.geomorph.2011.12.042 Romero-Saritama JM, Cueva-Ojeda DN (2020) Tamaño de semillas y germinación de Pernettya prostrata (Ericaceae): una especie del páramo andino. Caldasia 42(2):326–329. https://doi.org/10.15446/caldasia.v42n2.77247 Ruiz D, Moreno HA, Gutiérrez ME, Zapata PA (2008) Changing climate and endangered high mountain ecosystems in Colombia. Sci Total Environ 398(1–3):122–132. https://doi.org/10.1016/j.scitotenv.2008.02.038 Ruiz-Carrascal D, González-Duque D, Restrepo-Correa I (2022) Two-tiered reconstruction of Late Pleistocene to Holocene changes in the freezing level height in the largest glacierized areas of the Colombian Andes. J Mt Sci 19(3):615–636. https://doi.org/10.1007/s11629-021-6783-6 Salazar A, Gunnlaugsdóttir EG, Jónsdóttir IS, Klupar I, Wandji RPT, Arnalds Ó, Andrésson Ó (2024) Increased biocrust cover and activity in the highlands of Iceland after five growing seasons of experimental warming. Plant Soil 1–13. https://doi.org/10.1007/s11104-024-06900-7 Schmidt SK, Reed SC, Nemergut DR, Stuart Grandy A, Cleveland CC, Weintraub MN, Martin AM (2008) The earliest stages of ecosystem succession in high-elevation (5000 metres above sea level), recently deglaciated soils. Proceedings of the Royal Society B: Biological Sciences, 275(1653), 2793–2802. https://doi.org/10.1098/rspb.2008.0808 Schmidt SK, Cramm MA, Solon AJ, Bradley JA, Bueno de Mesquita CP, Cimpoiasu MO, Irons TP (2025) Biological soil crust microcolonies reveal how microbial communities assemble following retreat of a High Arctic glacier. FEMS microbes, xtaf007. https://doi.org/10.1093/femsmc/xtaf007 Tanner LH (2025) Distribution of Biological Soil Crusts on a Young Glacial Foreland in Southern Iceland and Their Role in Primary Succession. Land 14(9):1827 Tavili A, Jafari M, Chahouki MAZ, Sohrabi M (2017) How do cryptogams affect vascular plant establishment? Cryptogamie Bryologie 38(3):313–323. https://doi.org/10.3390/land14091827 Tovar C, Melcher I, Kusumoto B, Cuesta F, Cleef A, Meneses RI, Carilla J (2020) Plant dispersal strategies of high tropical alpine communities across the Andes. J Ecol 108(5):1910–1922. https://doi.org/10.1111/1365-2745.13416 Yoshitake S, Uchida M, Iimura Y, Ohtsuka T, Nakatsubo T (2018) Soil microbial succession along a chronosequence on a High Arctic glacier foreland, Ny-Ålesund, Svalbard: 10 years’ change. Polar Sci 16:59–67. https://doi.org/10.1016/j.polar.2018.03.003 Additional Declarations No competing interests reported. Supplementary Files TableS7.xlsx SalazaretalSupMaterial.docx Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 25 Mar, 2026 Reviews received at journal 24 Mar, 2026 Reviews received at journal 19 Mar, 2026 Reviewers agreed at journal 07 Mar, 2026 Reviewers agreed at journal 06 Mar, 2026 Reviewers invited by journal 06 Mar, 2026 Editor assigned by journal 06 Mar, 2026 Submission checks completed at journal 06 Mar, 2026 First submitted to journal 05 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9044279","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Short Report","associatedPublications":[],"authors":[{"id":603054594,"identity":"61e2ae36-7352-4d3c-be74-21987bdff9da","order_by":0,"name":"Alejandro Salazar","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAzUlEQVRIiWNgGAWjYDACdgYGAwYGZiCjuY0ZyOQhrIUZpoXnIAlaIKREYhszUe7ib2Y+UPBzh3U+v+TDtscFBQwy8g0EtEgcZksw7D2TbjlzdmK78QygwwwOELLmMI+BAW/bYQOD24lt0jwgLYR0yB/m/2D4F6Tl5kGIFoIOMzjMw2AMtuUGI0QLAyGHGR5mMzCWbUs3kOwB+oXHQIKwX+SONz8zfNtmbcDPfvjYY54/NvYEHQYEbMgeliCsHgiYHxClbBSMglEwCkYuAAD/pzZcFT8MNgAAAABJRU5ErkJggg==","orcid":"","institution":"Agricultural University of Iceland","correspondingAuthor":true,"prefix":"","firstName":"Alejandro","middleName":"","lastName":"Salazar","suffix":""},{"id":603054595,"identity":"ecc71ce6-c6f8-4961-8b68-f19cdca2cdf5","order_by":1,"name":"Maria E. Gutiérrez-Lagoueyte","email":"","orcid":"","institution":"Universidad EIA","correspondingAuthor":false,"prefix":"","firstName":"Maria","middleName":"E.","lastName":"Gutiérrez-Lagoueyte","suffix":""},{"id":603054596,"identity":"ddee01ba-0b7f-4d14-892e-e7fe677a60ce","order_by":2,"name":"Ingibjörg S. Jónsdóttir","email":"","orcid":"","institution":"University of Iceland","correspondingAuthor":false,"prefix":"","firstName":"Ingibjörg","middleName":"S.","lastName":"Jónsdóttir","suffix":""},{"id":603054597,"identity":"9dcd2822-10f8-494f-83c0-6fced44d9a75","order_by":3,"name":"Isabel C. Barrio","email":"","orcid":"","institution":"Agricultural University of Iceland","correspondingAuthor":false,"prefix":"","firstName":"Isabel","middleName":"C.","lastName":"Barrio","suffix":""},{"id":603054598,"identity":"2710c84b-d637-406f-ad64-d790697c99f8","order_by":4,"name":"Heiðrún I. Guðmundsdóttir","email":"","orcid":"","institution":"University of Iceland","correspondingAuthor":false,"prefix":"","firstName":"Heiðrún","middleName":"I.","lastName":"Guðmundsdóttir","suffix":""},{"id":603054599,"identity":"887ef8a8-d0a9-402d-9988-5e44a6ca36a8","order_by":5,"name":"Emilio Rodriguez-Caballero","email":"","orcid":"","institution":"University of Almería","correspondingAuthor":false,"prefix":"","firstName":"Emilio","middleName":"","lastName":"Rodriguez-Caballero","suffix":""},{"id":603054600,"identity":"08bf4bd1-e3f7-42c3-9361-1743575257ea","order_by":6,"name":"Adriana Sanchez-Andrade","email":"","orcid":"","institution":"Universidad del Rosario","correspondingAuthor":false,"prefix":"","firstName":"Adriana","middleName":"","lastName":"Sanchez-Andrade","suffix":""}],"badges":[],"createdAt":"2026-03-05 22:08:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9044279/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9044279/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104440057,"identity":"975d3644-e87f-43e2-819a-27672b4df30e","added_by":"auto","created_at":"2026-03-11 18:02:09","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":897705,"visible":true,"origin":"","legend":"\u003cp\u003eThe study site near the edge of the Conejeras glacier, Nevado Santa Isabel, Colombia (elevation and coordinates in Table S1). A) The stars indicate sampling locations along an elevational transect that represents a glacier forefield chronosequence covering dates from ca.1850 to 2020 (highest elevation, closest to the glacier edge). Satellite image from www.identify.plantnet.org. B) The PNN sign indicating the elevation where the edge of the glacier was in 2020. C) Schematic representation of the three sampling plots along each of the 60 m horizontal sampling transects used for the measurements at each location (see explanation in the main text).\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9044279/v1/3c9ad20803a34f4ecc68ca6f.png"},{"id":104780216,"identity":"d39149a1-74f9-4231-b8e4-6b136c68b924","added_by":"auto","created_at":"2026-03-17 07:51:27","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1008087,"visible":true,"origin":"","legend":"\u003cp\u003eA) The point-intercept device used to measure surface cover and roughness, B) The Jornada Experimental Range Soil Stability Test Kit used for estimations of soil stability, and C) Schematic representation indicating the number and location of cover (point intercepts) and roughness measurements within the 50 x 50 cm\u003csup\u003e2\u003c/sup\u003e quadrat.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9044279/v1/0dacf9dd687b83063f870507.png"},{"id":104440060,"identity":"8e8387b5-8fc6-473c-810b-de41356f0079","added_by":"auto","created_at":"2026-03-11 18:02:09","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":237891,"visible":true,"origin":"","legend":"\u003cp\u003eA) Surface cover of bare ground and rocks (grey, squares), lichens (yellow, upside-down triangles), bryophytes (light green, diamond), biocrust (brown, circles) and vascular plants (dark green, triangles), B) surface roughness (SD of the height of pins), and C) surface stability index, along the glacier forefield chronosequence at Conejeras. Points indicate means and horizontal lines show standard errors. N = 3.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9044279/v1/43ab7d30acfcd0c3512b80d2.png"},{"id":105033512,"identity":"b87e5f6c-d86d-44b5-ad04-87befdfcbb1f","added_by":"auto","created_at":"2026-03-20 07:18:54","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3465677,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9044279/v1/37b05ff1-1ac3-435c-8eaa-d46320d56e5d.pdf"},{"id":104780400,"identity":"6371c616-dc1f-4e47-809d-3c5f02363b90","added_by":"auto","created_at":"2026-03-17 07:52:47","extension":"xlsx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":15046,"visible":true,"origin":"","legend":"","description":"","filename":"TableS7.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-9044279/v1/364d7acdcaca443e2bc2463f.xlsx"},{"id":104808612,"identity":"aab34ad6-e9e7-42b0-9d60-f543713375a7","added_by":"auto","created_at":"2026-03-17 12:39:00","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":694350,"visible":true,"origin":"","legend":"","description":"","filename":"SalazaretalSupMaterial.docx","url":"https://assets-eu.researchsquare.com/files/rs-9044279/v1/522b384d9495bcf57fcef6b0.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Biocrust belt below the edge of a dying glacier in the Tropical Andes","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIn the high-elevation Tropical Andes, where glaciers are melting at a fast pace (Rabatel et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Ruiz et al., \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Ceballos et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2006\u003c/span\u003e, 2024), plant species of the p\u0026aacute;ramo and super-p\u0026aacute;ramo may be in a climate-driven race to higher elevations (Anthelme et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Cuesta et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; but see Chen et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). The success of their climbing depends on the dispersal and survival of reproductive organs, such as seeds (Tovar et al., \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). One of the key factors determining seedling survival and further plant development, particularly in these steep, erodible surfaces, is soil stability (Espigares et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), which can be enhanced by the development of biological soil crust, also referred to as biocrust (Belnap and B\u0026uuml;del, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Hu et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2002\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eBiocrusts are composed of soil particles held together by organisms such as cyanobacteria, lichen and bryophytes (Weber et al., 2022). Partly for this reason, surfaces covered with biocrusts are much more resistant to wind and water erosion than bare ground, where biocrust has been removed or has not yet developed (Belnap et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Chamizo et al., 2017). Also, the formation of biocrust can increase surface roughness (Rodr\u0026iacute;guez-Caballero et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), which in turn can increase seed entrapment (Elmarsdottir et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2003\u003c/span\u003e), especially in areas vulnerable to erosion, such as the forefield of a melting glacier. Furthermore, biocrusts can fix C and N (Elbert et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Rodriguez-Caballero et al., 2018; Reis et al., 2025), and reduce hydrological stress by increasing moisture retention during dry periods (Eldridge et al., 2020). Because of this, biocrusts often serve as safe sites for seedling establishment and growth (Behrend et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Aradottir and Halldorsson, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Tavili et al., \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). However, depending on site-specific conditions, seed features, and intrinsic properties of biocrust types, biocrusts can also have a negative or neutral effect on seedling development (Bacovcin et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Havrilla et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eMost of the scientific literature on biocrust comes from warm arid or semi-arid ecosystems (Weber et al., 2022). However, biocrusts are widespread in cold and mesic environments too, including at high-latitudes (Salazar et al., 2025; Pushkareva et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), and at high-elevation tropical ecosystems (Anthelme et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Llamb\u0026iacute; et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Schmidt et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). With ongoing climate change, biocrust cover is projected to decrease under all Representative Concentration Pathways (RCPs) in warm drylands (Rodriguez-Caballero et al., 2018). In contrast, in cold and mesic environments, biocrust cover may increase (Salazar et al., 2025; Mallen-Cooper et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), including in newly exposed areas after the melting of glaciers (Tanner, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Schmidt et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2008\u003c/span\u003e and \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Yoshitake et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Breen and L\u0026eacute;vesque, 2008). In these environments, biocrust-forming organisms are among the first colonizers and the development of biocrusts may play a key role in primary succession, by determining surface stability and whether and which plant species establish; as well as when, and how fast they grow, thus influencing the successional trajectory.\u003c/p\u003e \u003cp\u003eTo deepen our understanding of the role biocrusts play in primary succession within glacial environments, we used a space-for-time approach to examine a well-defined chronosequence along the forefield of the Conejeras glacier, at the Santa Isabel Nevado \u0026mdash;one of the glaciers with the highest area loss rate per year in Colombia (Rabatel et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2018\u003c/span\u003e, Ceballos et al., 2024). Most research at this glacial forefield has focused on the monitoring of ice mass and cover (e.g., Ruiz-Carrascal et al., \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Rabatel et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Ceballos et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Poveda and Pineda, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2009\u003c/span\u003e) and on the composition (Anthelme et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) and activity (Meyers et al., \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) of plant communities. Here, we aimed at contributing to this research by investigating the potential role of biocrust in primary succession through surface colonization, soil surface stabilization and plant establishment facilitation. According to succession theory, we expected to find changes in biocrust and vegetation development from recently deglaciated areas closer to the edge of the glacier, to areas farther away where the glacier retreated longer ago. We hypothesized that biocrust cover would be highest near the glacier edge and decrease at lower elevations, where vascular plants have had more time to establish and expand. Overall, we expect this research to shed light on the role of biocrusts as potential key regulators of ecological succession as Tropical glaciers in the Andes and in comparable ecosystems melt.\u003c/p\u003e"},{"header":"Methods and materials","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy site\u003c/h2\u003e \u003cp\u003eWe tested our hypotheses at a glacier forefield chronosequence (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA) set by Anthelme et al. (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), near the edge of the glacier Conejeras, Nevado Santa Isabel, Colombia (4\u0026deg; 49\u0026prime; 12.9324'' N 75\u0026deg; 22\u0026prime; 33.2112'' W). The chronosequence is located between ca. 4350 and 4700 m.a.s.l. The mean (2013\u0026ndash;2017) annual temperature and precipitation at the edge of the glacier are 1.3\u0026deg;C and 1025 mm, respectively (Anthelme et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Mor\u0026aacute;n-Tejeda et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe National Natural Parks of Colombia (PNN, after its Spanish abbreviation) and the Institute of Hydrology, Meteorology and Environmental Studies (IDEAM, after its Spanish abbreviation) marked the edge of the glacier in 2020, 2010, 1990, 1960 and ca. 1850 along an elevational gradient (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA, B). These locations represent a chronosequence of glacier retreat where we conducted our field survey on June 17th, 2025. At each of these locations, we established a 60-m horizontal transect, positioned ca. 5 m downhill approximately along the contour line (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eC) where we measured surface cover, roughness, and stability. At the lowest sampling location, corresponding to the location of the glacier edge in ca. 1850, the PNN sign is placed on the glacier\u0026rsquo;s moraine. Since our goal was to study the soil and plant communities after the glacier retreat, in this case, we located the transect ca. 50 m uphill, beyond an area disturbed by the construction of a wooden trail (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e,H).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSurface cover, roughness and stability\u003c/h3\u003e\n\u003cp\u003eAt each of the sampling locations we measured surface cover in three 50 x 50 cm\u003csup\u003e2\u003c/sup\u003e, evenly distributed along the horizontal transect using the point-intercept method (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA,C). We used a light point-intercept device with a single row of points along a 50 cm long stick (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA), and recorded surface cover in a grid with nine evenly distributed points by moving the instrument twice (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC). In each point, we recorded bare-ground (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e,A) and rocks (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e,B), as well as the occurrence of biocrusts dominated by cyanobacteria (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e,C), lichens (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e,D) or bryophytes (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e,E), and non-crusted lichens (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e,F), non-crusted-bryophytes (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e, G) and vascular plants (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e,H). When bryophytes and lichens were not part of a crusted system, but rather formed a carpet or a foliose structure (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e,F and G), they were recorded as such. Since. When the same species was hit (intercepted) multiple times in the same point, we recorded it (Table S7) but only used the first hit to calculate cover. At the same time, we measured surface roughness similar to Mallen-Cooper et al. (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA,C). Specifically, in 9 points at 5 cm intervals along the uppermost row of the plot grid we recorded the distance between the top of the pin and the horizontal bar of the point-intercept device (9 points in total; Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC), and estimated surface roughness based on the standard deviation (SD) of the pin heights. Since we measured roughness along contour lines, slope did not have a major influence on the measurements (e.g., Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA) and therefore we did not remove it before calculating SDs. Finally, we measured surface (1\u0026ndash;2 cm) stability with a Jornada Experimental Range Soil Stability Test Kit (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB,C), as described by Herrick et al. (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2001\u003c/span\u003e). For the latter, we took three samples per quadrat, along the uppermost row for the point intercept analysis (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFrom field measurements, we calculated the percentage cover of five different cover types: biocrust, bryophytes, lichens, vascular plants, and bare ground and rocks (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e) as follows:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$Cover\\left(\\%\\right)=\\left(\\frac{Numberofhitsforacovertype}{Totalnumberofpointsingrid}\\right)\\times100$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere the total number of points in a grid was 9 (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC).\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eWe used linear mixed effects models (LMMs) to analyze surface roughness, stability and cover along the glacier forefield chronosequence. In the case of surface cover, in which we used one LMM per cover type, the models included the fixed effects of elevation and the random effects of the location of the grids within transects. Since we hypothesized a non-linear change of biocrust cover along the chronosequence, with biocrust cover peaking at high but not the highest elevation where glacial retreat is most recent and biocrust has not had time to develop, we included a quadratic term for elevation in the LMMs. We used the Akaike Information Criterion (AIC) to compare the performance of the models with and without the quadratic term. Considering the focus of our hypothesis, as well as the relatively small size of our dataset, we grouped the cover data into five categories: vascular plants, non-biocrust bryophytes, non-biocrust lichens, biocrust, and rocks and bare ground. However, when possible, we recorded and analyzed surface cover in more detail, for example, in the case of biocrusts with different dominant components: cyanobacteria, lichens or liverworts.\u003c/p\u003e \u003cp\u003eTo be able to compare potential non-linear behaviors of surface roughness and stability, related to biocrust cover, we also included a quadratic term for elevation (or site age) in the roughness and stability LMMs. We considered each of the three grids in the 60 m transects (one per elevation level) as replicates (N\u0026thinsp;=\u0026thinsp;3). We used R (R core team, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2025\u003c/span\u003e), version 4.5.2, for all statistical analyses and. For the LMMs, we used the \u003cem\u003elme4\u003c/em\u003e (Bates et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2015\u003c/span\u003e) and \u003cem\u003elmerTest\u003c/em\u003e (Kuznetsova et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) packages.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results and discussion","content":"\u003cp\u003eOur findings highlight two major successional events along the glacier forefield chronosequence at Conejeras: a primary succession characterized by bryophyte growth and the development of biocrust, as well as by an increase in surface roughness and stability, at a high but not the highest elevation near the edge of the glacier; followed by an increase in the cover of vascular plants that replaced biocrust and bare ground, at lower elevations (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e; Tables S2-6). Our space-for-time substitution approach suggests that biocrust, followed by bryophytes and lichens, became the dominant biological feature of the soil surface 15\u0026nbsp;year after the retreat of the glacier (4690 m.a.s.l.). Biocrust cover reached a maximum of ca. 50% of the total surface after 35 yrs (4660 m.a.s.l.), and remained a main feature of the surface after 65 yrs (4648 m.a.s.l.; Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA, Table S3) \u0026mdash;the hypothesized biocrust belt. Beyond this location, at lower elevations, biocrust cover decreased and vascular plant cover increased, which together with findings discussed below, suggests a facilitating effect of biocrust on vascular plant establishment during primary succession in alpine environments or similar.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe estimated time needed for biocrust development on bare surfaces at the Conejeras area is comparable to those observed in other glacier forefield chronosequences, both in alpine environments in the Tropical Andes (Llambi et al., 2021) and in glacial forefields at high latitudes (Tanner, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Yoshitake et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Breen and L\u0026eacute;vesque, 2008). Also, the higher abundance of cyanobacteria-dominated biocrust on the highest and youngest stages of the chronosequence, compared to the more lichen- and bryophyte-dominated biocrusts in the lower parts (Table S7), follows the expected succession within the biocrust communities (Maier et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; but see Kidron and Xiao, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). However, the role of biocrust in ecological succession after the melting of glaciers can vary between sites depending on abiotic conditions and intrinsic biocrust-vegetation relationships.\u003c/p\u003e \u003cp\u003eIn a similar study at the North-West flank of the glacier forefront at Humboldt peak, in the Sierra Nevada National Park, Venezuela, biocrust covered almost 80% of the surface 10 yrs after the edge of the glacier retreated (Llambi et al., 2021). At lower sites, corresponding to the locations of the edge of the glacier up to 109 yrs after it retreated, biocrust cover decreased as in our study, but still remained the dominant feature of the ecosystem, covering 50\u0026ndash;60% of the total surface (Llambi et al., 2021). This suggests that either abiotic components such as climate were halting ecological succession, or that biocrusts acted as a barrier for the establishment of vascular plants (e.g., as in Gilbert and Corbin, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Lichen-dominated biocrusts, which are widespread at the glacier forefront at Humboldt peak (Llambi et al., 2021), often have neutral or negative effects on seedling emergence (Bacovcin et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Havrilla et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). In contrast, cyanobacteria-dominated biocrust, characterized by dark pigmentation (Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA and S1,B), and which was the most abundant biocrust type at the biocrust belt in our site (Table S7), often facilitates seedling emergence (Bacovcin et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; but see Havrilla et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), especially of medium-size (0.51-1 g/1000 seeds) and large (1.1\u0026thinsp;+\u0026thinsp;g/1000 seeds) seeds (Bacovcin et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). The most abundant (0\u0026ndash;15% cover) vascular plant growth form at the biocrust belt at the Conejeras glacier were graminoids, such as those of the \u003cem\u003eFestuca\u003c/em\u003e genus (Table S7; see also Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA), followed by the dwarf evergreen shrub \u003cem\u003eGaultheria myrsinoides\u003c/em\u003e(Table S7). \u003cem\u003eFestuca\u003c/em\u003e seeds, which generally weigh more than 1g/1000 seeds (L\u0026oacute;pez et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Fairey and Lefkovitch, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1996\u003c/span\u003e), are approximately one order of magnitude heavier than those of \u003cem\u003eGaultheria myrsinoides\u003c/em\u003e (Romero-Saritama et al., 2020). The positive effect of cyanobacteria-dominated biocrust on large seed establishment \u0026mdash;i.e., its role as a biological filer influencing plant species composition\u0026mdash;, could partially explain why graminoids were the dominant vascular plant in the biocrust belt on the glacier forefield chronosequence at the Conejeras glacier, and shed light on possible trajectories of ecological succession in Tropical p\u0026aacute;ramos and superp\u0026aacute;ramos, as glaciers continue melting.\u003c/p\u003e \u003cp\u003eAt a comparable glacier forefield chronosequence in southern Iceland, biocrust covered ca. 25% of a moraine surface ca. 20 yrs after being exposed by glacier retreat (Tanner, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). As in our study site, biocrust cover decreased along the chronosequence, down to ca. 5% in areas corresponding to the location of the edge of the glacier in 1965 and 1954. However, contrary to the expected trend according to successional theory, biocrust cover increased again to ca 25% in the area corresponding to the glacier edge in 1946, and decreased as expected afterwards. In this case, biocrust cover seems to have been influenced by topography and climate as well: the two areas with the highest biocrust cover in the glacier forefield chronosequence in southern Iceland were those topographically lowest and most sheltered (Tanner, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). At the forefield chronosequence of the Conejeras glacier, the decrease in biocrust cover at 4648 m.a.s.l., immediately below the area with a maximum biocrust cover of ca. 50%, was partly due to the presence of large rocks (Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA and S1,E). Together, our results and related research highlight the key role of biocrusts in primary succession in newly exposed areas after glacier melting, and show how biocrust-vegetation relationships can be affected by abiotic factors such as climate and geomorphological formations.\u003c/p\u003e \u003cp\u003eFrom a mechanistic perspective, our results of soil roughness and stability increasing with biocrust cover (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e; Tables S8 and 9) contribute to the body of research highlighting these two as key processes through which biocrusts influence seed trapping, seedling establishment, and ultimately primary ecological succession (Chamizo et al., 2017; Belnap and B\u0026uuml;del, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Rodr\u0026iacute;guez-Caballero et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Elmarsdottir et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). The statistical significance of the non-linear change of soil roughness with elevation was marginal (Table S8). This could reflect that roughness was not only affected by the presence or absence of biocrust, which also had a marginal, non-linear behavior with elevation (Table S3), but also by other features of the ecosystem such as vegetation and rocks. Moreover, it could indicate that at Conejeras, biocrusts play a larger role in ecological succession via increases in soil stability, which had a strong non-linear response to elevation (Table S9). Despite the weak statistical significance of the non-linear variation of surface roughness with elevation, the largest relative increase in roughness along the chronosequence was between the highest-elevation site dominated by bare ground and the next lower elevation site, where the dominant biological features were bryophytes and biocrust. Rougher surfaces reduce overland flow speed, which can promote microdepressions and indirectly affect sediment loss and successional dynamics (Rodr\u0026iacute;guez-Caballero et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Overall, our findings and numerous observations of biocrust increasing surface roughness (Ji et al., 2025; Caster et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Rodr\u0026iacute;guez-Caballero et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), suggest that at the Conejeras site, roughness may play an important role in seed entrapment and eventual seedling establishment.\u003c/p\u003e \u003cp\u003eSoil stability was lowest at the highest elevation, entirely covered by bare ground and rocks (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e,A), then it substantially increased at lower elevations, peaking at the area primarily covered by biocrust (4,660 m), and remained high at the lowest points where biocrusts are replaced by vascular plants (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA,C; Table S9). Our finding is similar to one at the Piedras Blancas p\u0026aacute;ramo in Venezuela, where the formation of biocrust increased surface resistance to raindrop erosion by ca. 5 times compared to non-crusted soil (P\u0026eacute;rez, 1997). The positive effect of biocrust formation on soil stability may be more consequential for seedling establishment in steep glacier forefields prone to runoff erosion, like at Conejeras and similar alpine environments, than in less steep ones. In addition to soil stability, there are other factors that can affect seedling performance and that were not included in our analysis, such as nitrogen fixation (Salazar et al., 2022) or water regulation (Eldridge et al., 2020). It remains to be understood to what extent these mechanisms play a role in the ongoing ecological succession at the Conejeras area and similar glacier forefields.\u003c/p\u003e \u003cp\u003eFinally, not all bryophytes and lichens along the Conejeras chronosequence were part of a biocrust community. Some bryophytes formed non-crusted structures such as mats or cushions (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e,G; Table S7), and likewise, some lichens formed lichen-only crustose or foliose structures (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e,F; Table S7). Non-crusted bryophytes can increase seed entrapment too (Linskens et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e1993\u003c/span\u003e). However, they seem to facilitate seedling establishment only when the bryophyte is very small (e.g., 1 cm or less; Behrend et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2025\u003c/span\u003e), which in many cases may mean that it is part of a biocrust community. When the bryophyte is taller, seeds can be trapped, but they do not reach the ground and therefore do not develop (Behrend et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). Lichens can increase seedling recruitment too (Nystuen et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). However, when they become dominant, they often act like a shield or hardened barrier that prevents the establishment of vascular plants (Bacovcin et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Havrilla et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Immediately below the highest and youngest stages of the Conejeras chronosequence, biocrust cover was higher than that of non-crusted bryophytes and lichens. On the other hand, at the lower and oldest sites, the cover of non-crusted bryophytes and lichens was 20\u0026ndash;30%, whereas that of biocrust was ca. 0% (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA). This could be an indicator of a more effective primary colonization of newly exposed soil by biocrust than by individual bryophytes and lichens, as well as more growth of vascular plants on biocrust than on bryophyte- and lichen-only structures.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eBiocrust development on the highest and youngest stages of the Conejeras chronosequence increases the roughness and stability of the soil surface, which can facilitate the establishment of vascular plants, especially those with large seeds. Our space-for-time analysis indicates that biocrust development starts a few years after the glacier retreats, and together with bryophytes and lichens becomes the dominant feature of the surface. In this elevational range, which in our study covered the area corresponding to 15\u0026ndash;65 yrs after the melting of the glacier (4648\u0026ndash;4660 m.a.s.l.) \u0026mdash;the biocrust belt\u0026mdash;, biocrusts play a key role in the functioning of the ecosystem, including in the roughness and stability of the surface, and therefore indirectly on hydrological dynamics, nutrient cycling and ecological succession. Overall, our findings represent one additional piece of evidence and perspective to understand the key role of biocrust on primary succession and the ecological dynamics that follow the rapid melting of glaciers in the Tropical Andes.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was conducted during the summer course \u003cem\u003eTundra meets the p\u0026aacute;ramo\u003c/em\u003e, organized by the Agricultural University of Iceland (AUI) in collaboration with Del Rosario University and EIA University, Colombia; and the University of Iceland and University of Akureyri, Iceland. We thank all the people involved in the preparation of this course and research, and the local collaborators, especially the PNN, including the park ranger Alfredo Ba\u0026ntilde;ol, who helped with the collection of soil stability data. Also, we thank \u0026THORN;\u0026oacute;rey B. Bj\u0026ouml;rnsd\u0026oacute;ttir for her help in collecting point-intercept data. ERC is supported by the Ramon y Cajal fellowship (RYC2020-030762-I) and projects SOLARID2Envi (reference PID2024\u0026ndash;161692OB-C31) and CNS2024-154916 funded by MICIU/AEI /10.13039/501100011033 and UE NextGenerationEU/PRTR. This research involves a collaboration of the AUI and the University of Almer\u0026iacute;a, two partners of the UNIgreen alliance. \u0026nbsp;\u003c/p\u003e\n"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAnthelme F, Carrasquer I, Ceballos JL, Peyre G (2022) Novel plant communities after glacial retreat in Colombia:(many) losses and (few) gains. Alp Bot 132(2):211\u0026ndash;222. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00035-022-00282-1\u003c/span\u003e\u003cspan address=\"10.1007/s00035-022-00282-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAradottir AL, Halldorsson G (2018) Colonization of woodland species during restoration: seed or safe site limitation? Restor Ecol 26:S73\u0026ndash;S83. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/rec.12645\u003c/span\u003e\u003cspan address=\"10.1111/rec.12645\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBacovcin J, McIntyre C, Havrilla CA (2025) Morphological Seed Traits Structure Relationships Between Biocrusts and Plant Emergence. Ecol Evol 15(6):e71450. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/ece3.71450\u003c/span\u003e\u003cspan address=\"10.1002/ece3.71450\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBates D, M\u0026auml;chler M, Bolker B, Walker S (2015) Fitting linear mixed-effects models using lme4. J Stat Softw 67:1\u0026ndash;48. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://doi.org/10.18637/jss.v067.i01\u003c/span\u003e\u003cspan address=\"10.18637/jss.v067.i01\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBehrend AM, Arad\u0026oacute;ttir \u0026Aacute;L, Svavarsd\u0026oacute;ttir K, Th\u0026oacute;rhallsd\u0026oacute;ttir TE, Pommerening A (2025) Natural colonization as a means to upscale restoration of subarctic woodlands in Iceland. Restor Ecol 33(1):e14332. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/rec.14332\u003c/span\u003e\u003cspan address=\"10.1111/rec.14332\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBelnap J, B\u0026uuml;del B (2016) Biological soil crusts as soil stabilizers. Biological soil crusts: an organizing principle in drylands. Springer International Publishing, Cham, pp 305\u0026ndash;320. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/978-3-319-30214-0_16\u003c/span\u003e\u003cspan address=\"10.1007/978-3-319-30214-0_16\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBelnap J, Walker BJ, Munson SM, Gill RA (2014) Controls on sediment production in two US deserts. Aeolian Res 14:15\u0026ndash;24. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.aeolia.2014.03.007\u003c/span\u003e\u003cspan address=\"10.1016/j.aeolia.2014.03.007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBreen K, L\u0026eacute;vesque E, Arctic (2008) Antarct Alp Res, 40(2), 287\u0026ndash;297. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1657/1523-0430(06-098)[BREEN]2.0.CO;2\u003c/span\u003e\u003cspan address=\"10.1657/1523-0430(06-098)[BREEN]2.0.CO;2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCaster J, Sankey TT, Sankey JB, Bowker MA, Buscombe D, Duniway MC, Joyal T (2021) Biocrust and the soil surface: Influence of climate, disturbance, and biocrust recovery on soil surface roughness. Geoderma 403:115369. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.geoderma.2021.115369\u003c/span\u003e\u003cspan address=\"10.1016/j.geoderma.2021.115369\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCeballos Li\u0026eacute;vano JL, Mendoza C, Mart\u0026iacute;nez AF, Serrano S y, Zuluaga C\u0026aacute;rdenas LC (2024) Informe del estado de los glaciares colombianos 2023. Instituto de Hidrolog\u0026iacute;a, Meteorolog\u0026iacute;a y Estudios Ambientales - Ideam. ISSN: 2806\u0026thinsp;\u0026ndash;\u0026thinsp;0261. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://archivo.ideam.gov.co/web/ecosistemas/investigacion-publicaciones\u003c/span\u003e\u003cspan address=\"http://archivo.ideam.gov.co/web/ecosistemas/investigacion-publicaciones\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Accessed on 18/12/2025\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCeballos JL, Eusc\u0026aacute;tegui C, Ram\u0026iacute;rez J, Ca\u0026ntilde;on M, Huggel C, Haeberli W, Machguth H (2006) Fast shrinkage of tropical glaciers in Colombia. Ann Glaciol 43:194\u0026ndash;201. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3189/172756406781812429\u003c/span\u003e\u003cspan address=\"10.3189/172756406781812429\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen YH, Lenoir J, Chen IC (2025) Limited evidence for range shift\u0026ndash;driven extinction in mountain biota. Science 388(6748):741\u0026ndash;747. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://doi.org/10.1126/science.adq9512\u003c/span\u003e\u003cspan address=\"10.1126/science.adq9512\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCorbin JD, Thiet RK (2020) Temperate biocrusts: mesic counterparts to their better-known dryland cousins. Front Ecol Environ 18(8):456\u0026ndash;464. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/fee.2234\u003c/span\u003e\u003cspan address=\"10.1002/fee.2234\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCuesta F, Carilla J, LLamb\u0026iacute; LD, Muriel P, Lencinas MV, Meneses RI, Tovar C (2023) Compositional shifts of alpine plant communities across the high Andes. Glob Ecol Biogeogr 32(9):1591\u0026ndash;1606. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/geb.13721\u003c/span\u003e\u003cspan address=\"10.1111/geb.13721\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eElbert W, Weber B, Burrows S, Steinkamp J, B\u0026uuml;del B, Andreae MO, P\u0026ouml;schl U (2012) Contribution of cryptogamic covers to the global cycles of carbon and nitrogen. Nat Geosci 5:459\u0026ndash;462. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/ngeo1486\u003c/span\u003e\u003cspan address=\"10.1038/ngeo1486\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eElmarsdottir A, Aradottir AL, Trlica MJ (2003) Microsite availability and establishment of native species on degraded and reclaimed sites. J Appl Ecol 40(5):815\u0026ndash;823. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1046/j.1365-2664.2003.00848.x\u003c/span\u003e\u003cspan address=\"10.1046/j.1365-2664.2003.00848.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEspigares T, Moreno-de las Heras M, Nicolau JM (2011) Performance of vegetation in reclaimed slopes affected by soil erosion. Restor Ecol 19(1):35\u0026ndash;44. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1526-100X.2009.00546.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1526-100X.2009.00546.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFairey NA, Lefkovitch LP (1996) Ploidy and cultivar group differences in the thousand-seed weight of red fescue (Festuca rubra L). Can J Plant Sci 76(3):465\u0026ndash;467. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.4141/cjps96-082\u003c/span\u003e\u003cspan address=\"10.4141/cjps96-082\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGilbert JA, Corbin JD (2019) Biological soil crusts inhibit seed germination in a temperate pine barren ecosystem. PLoS ONE 14(2):e0212466. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1371/journal.pone.0212466\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0212466\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKidron GJ, Xiao B (2024) A false paradigm? Do biocrust types necessarily reflect \u0026lsquo;successional stages\u0026rsquo;? Ecohydrology 17(1):e2610. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/eco.2610\u003c/span\u003e\u003cspan address=\"10.1002/eco.2610\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKuznetsova A, Brockhoff PB, Christensen RH (2017) lmerTest package: tests in linear mixed effects models. J Stat Softw 82:1\u0026ndash;26. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://doi.org/10.18637/jss.v082.i13\u003c/span\u003e\u003cspan address=\"10.18637/jss.v082.i13\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHavrilla CA, Chaudhary VB, Ferrenberg S, Antoninka AJ, Belnap J, Bowker MA, Barger NN (2019) Towards a predictive framework for biocrust mediation of plant performance: a meta-analysis. J Ecol 107(6):2789\u0026ndash;2807. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/1365-2745.13269\u003c/span\u003e\u003cspan address=\"10.1111/1365-2745.13269\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHerrick JE, Whitford WG, De Soyza AG, Van Zee JW, Havstad KM, Seybold CA, Walton M (2001) Field soil aggregate stability kit for soil quality and rangeland health evaluations. CATENA 44(1):27\u0026ndash;35\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHu C, Liu Y, Song L, Zhang D (2002) Effect of desert soil algae on the stabilization of fine sands. J Appl Phycol 14(4):281\u0026ndash;292. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0341-8162(00)00173-9\u003c/span\u003e\u003cspan address=\"10.1016/S0341-8162(00)00173-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLaureen Drahorad S, Felix-Henningsen P (2012) An electronic micropenetrometer (EMP) for field measurements of biological soil crust stability. J Plant Nutr Soil Sci 175(4):519\u0026ndash;520. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/jpln.201200026\u003c/span\u003e\u003cspan address=\"10.1002/jpln.201200026\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLinskens HF, Bargagli R, Cresti M, Focardi S (1993) Entrapment of long-distance transported pollen grains by various moss species in coastal Victoria Land. Antarctica Polar Biology 13(2):81\u0026ndash;87. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/BF00238539\u003c/span\u003e\u003cspan address=\"10.1007/BF00238539\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLlamb\u0026iacute; LD, Melfo A, G\u0026aacute;mez LE, Pelayo RC, C\u0026aacute;rdenas M, Rojas C, Hern\u0026aacute;ndez J (2021) Vegetation assembly, adaptive strategies and positive interactions during primary succession in the forefield of the last Venezuelan glacier. Front Ecol Evol 9:657755. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3389/fevo.2021.657755\u003c/span\u003e\u003cspan address=\"10.3389/fevo.2021.657755\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eL\u0026oacute;pez AS, L\u0026oacute;pez DR, Arana MV, Batlla D, Marchelli P (2021) Germination response to water availability in populations of Festuca pallescens along a Patagonian rainfall gradient based on hydrotime model parameters. Sci Rep 11(1):10653. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/s41598-021-89901-1\u003c/span\u003e\u003cspan address=\"10.1038/s41598-021-89901-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMaier S, Tamm A, Wu D, Caesar J, Grube M, Weber B (2018) Photoautotrophic organisms control microbial abundance, diversity, and physiology in different types of biological soil crusts. ISME J 12(4):1032\u0026ndash;1046. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/s41396-018-0062-8\u003c/span\u003e\u003cspan address=\"10.1038/s41396-018-0062-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMallen-Cooper M, Bowker MA, Antoninka AJ, Eldridge DJ (2020) A practical guide to measuring functional indicators and traits in biocrusts. Restor Ecol 28:S56\u0026ndash;S66. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/rec.12974\u003c/span\u003e\u003cspan address=\"10.1111/rec.12974\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMallen-Cooper M, Rodr\u0026iacute;guez‐Caballero E, Eldridge DJ, Weber B, B\u0026uuml;del B, H\u0026ouml;hne H, Cornwell WK (2023) Towards an understanding of future range shifts in lichens and mosses under climate change. J Biogeogr 50(2):406\u0026ndash;417. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/jbi.14542\u003c/span\u003e\u003cspan address=\"10.1111/jbi.14542\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMeyers B, Guti\u0026eacute;rrez-Lagoueyte ME, Tobon C (2023) Measurement of actual evapotranspiration in a p\u0026aacute;ramo ecosystem using portable closed chambers: Comparison between giant rosettes, tussock grasses and shrubs. Ecohydrology 16(4):e2525. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/eco.2525\u003c/span\u003e\u003cspan address=\"10.1002/eco.2525\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMor\u0026aacute;n-Tejeda E, Ceballos JL, Pe\u0026ntilde;a K, Lorenzo-Lacruz J, L\u0026oacute;pez-Moreno JI (2018) Hydrol Earth Syst Sci 22(10):5445\u0026ndash;5461. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.5194/hess-22-5445-2018\u003c/span\u003e\u003cspan address=\"10.5194/hess-22-5445-2018\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Recent evolution and associated hydrological dynamics of a vanishing tropical Andean glacier: Glaciar de Conejeras, Colombia\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNystuen KO, Sundsdal K, Opedal \u0026Oslash;H, Holien H, Strimbeck GR, Graae BJ (2019) Lichens facilitate seedling recruitment in alpine heath. J Veg Sci 30(5):868\u0026ndash;880. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/jvs.12773\u003c/span\u003e\u003cspan address=\"10.1111/jvs.12773\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePoveda G, Pineda K (2009) Reassessment of Colombia's tropical glaciers retreat rates: are they bound to disappear during the 2010\u0026ndash;2020 decade? Advances in Geosciences. 22:107\u0026ndash;116. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.5194/adgeo-22-107-2009\u003c/span\u003e\u003cspan address=\"10.5194/adgeo-22-107-2009\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePushkareva E, Johansen JR, Elster J (2016) A review of the ecology, ecophysiology and biodiversity of microalgae in Arctic soil crusts. Polar Biol 39(12):2227\u0026ndash;2240. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00300-016-1902-5\u003c/span\u003e\u003cspan address=\"10.1007/s00300-016-1902-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eR Core Team (2025) R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria. \u0026lt;\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.R-project.org/\u003c/span\u003e\u003cspan address=\"https://www.R-project.org/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRabatel A, Ceballos JL, Micheletti N, Jordan E, Braitmeier M, Gonz\u0026aacute;lez J, Zemp M (2018) Toward an imminent extinction of Colombian glaciers? Geogr Annaler: Ser Phys Geogr 100(1):75\u0026ndash;95. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/04353676.2017.1383015\u003c/span\u003e\u003cspan address=\"10.1080/04353676.2017.1383015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRodr\u0026iacute;guez-Caballero E, Cant\u0026oacute;n Y, Chamizo S, Afana A, Sol\u0026eacute;-Benet A (2012) Effects of biological soil crusts on surface roughness and implications for runoff and erosion. Geomorphology 145:81\u0026ndash;89. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.geomorph.2011.12.042\u003c/span\u003e\u003cspan address=\"10.1016/j.geomorph.2011.12.042\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRomero-Saritama JM, Cueva-Ojeda DN (2020) Tama\u0026ntilde;o de semillas y germinaci\u0026oacute;n de Pernettya prostrata (Ericaceae): una especie del p\u0026aacute;ramo andino. Caldasia 42(2):326\u0026ndash;329. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.15446/caldasia.v42n2.77247\u003c/span\u003e\u003cspan address=\"10.15446/caldasia.v42n2.77247\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRuiz D, Moreno HA, Guti\u0026eacute;rrez ME, Zapata PA (2008) Changing climate and endangered high mountain ecosystems in Colombia. Sci Total Environ 398(1\u0026ndash;3):122\u0026ndash;132. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.scitotenv.2008.02.038\u003c/span\u003e\u003cspan address=\"10.1016/j.scitotenv.2008.02.038\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRuiz-Carrascal D, Gonz\u0026aacute;lez-Duque D, Restrepo-Correa I (2022) Two-tiered reconstruction of Late Pleistocene to Holocene changes in the freezing level height in the largest glacierized areas of the Colombian Andes. J Mt Sci 19(3):615\u0026ndash;636. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11629-021-6783-6\u003c/span\u003e\u003cspan address=\"10.1007/s11629-021-6783-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSalazar A, Gunnlaugsd\u0026oacute;ttir EG, J\u0026oacute;nsd\u0026oacute;ttir IS, Klupar I, Wandji RPT, Arnalds \u0026Oacute;, Andr\u0026eacute;sson \u0026Oacute; (2024) Increased biocrust cover and activity in the highlands of Iceland after five growing seasons of experimental warming. Plant Soil 1\u0026ndash;13. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11104-024-06900-7\u003c/span\u003e\u003cspan address=\"10.1007/s11104-024-06900-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchmidt SK, Reed SC, Nemergut DR, Stuart Grandy A, Cleveland CC, Weintraub MN, Martin AM (2008) The earliest stages of ecosystem succession in high-elevation (5000 metres above sea level), recently deglaciated soils. Proceedings of the Royal Society B: Biological Sciences, 275(1653), 2793\u0026ndash;2802. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1098/rspb.2008.0808\u003c/span\u003e\u003cspan address=\"10.1098/rspb.2008.0808\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchmidt SK, Cramm MA, Solon AJ, Bradley JA, Bueno de Mesquita CP, Cimpoiasu MO, Irons TP (2025) Biological soil crust microcolonies reveal how microbial communities assemble following retreat of a High Arctic glacier. FEMS microbes, xtaf007. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/femsmc/xtaf007\u003c/span\u003e\u003cspan address=\"10.1093/femsmc/xtaf007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTanner LH (2025) Distribution of Biological Soil Crusts on a Young Glacial Foreland in Southern Iceland and Their Role in Primary Succession. Land 14(9):1827\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTavili A, Jafari M, Chahouki MAZ, Sohrabi M (2017) How do cryptogams affect vascular plant establishment? Cryptogamie Bryologie 38(3):313\u0026ndash;323. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/land14091827\u003c/span\u003e\u003cspan address=\"10.3390/land14091827\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTovar C, Melcher I, Kusumoto B, Cuesta F, Cleef A, Meneses RI, Carilla J (2020) Plant dispersal strategies of high tropical alpine communities across the Andes. J Ecol 108(5):1910\u0026ndash;1922. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/1365-2745.13416\u003c/span\u003e\u003cspan address=\"10.1111/1365-2745.13416\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYoshitake S, Uchida M, Iimura Y, Ohtsuka T, Nakatsubo T (2018) Soil microbial succession along a chronosequence on a High Arctic glacier foreland, Ny-\u0026Aring;lesund, Svalbard: 10 years\u0026rsquo; change. Polar Sci 16:59\u0026ndash;67. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.polar.2018.03.003\u003c/span\u003e\u003cspan address=\"10.1016/j.polar.2018.03.003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"alpine-botany","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"albo","sideBox":"Learn more about [Alpine Botany](http://link.springer.com/journal/35)","snPcode":"35","submissionUrl":"https://www.editorialmanager.com/albo/default2.aspx","title":"Alpine Botany","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Biological soil crust (biocrust), vascular plants, páramo, ecological succession, glacier chronosequence, climate change","lastPublishedDoi":"10.21203/rs.3.rs-9044279/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9044279/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eLife can be unstable. This is especially true for seedlings growing on erodible surfaces, such as newly exposed areas after glacier retreat. Here we used a space-for-time approach to study the role of biological soil crust (biocrust) as surface stabilizer and facilitator of ecological succession along a glacier forefield chronosequence at the retreating Conejeras glacier in the Tropical Andes. We used the point-intercept method to estimate surface cover of plants, biocrust, bare ground and rocks, as well as surface roughness; and a field soil aggregate kit to estimate soil stability. As hypothesized, following a bare-ground stage near the edge of the glacier, the successional trajectory involved the development of a biocrust belt, including bryophytes and lichens, followed by an increasing vascular plant cover in more advanced successional stages. The development of biocrust was accompanied by higher roughness and stability, which likely increased seed entrapment and seedling establishment. Our results suggest that the development of cyanobacterial-dominated biocrust at the forefield of the Conejeras glacier may favor the establishment of plants with large seeds, such as graminoids from the \u003cem\u003eFestuca\u003c/em\u003e genus. Overall, our findings highlight the key role of biocrusts in the ecological dynamics that follow glacier melt in the Tropical Andes.\u003c/p\u003e","manuscriptTitle":"Biocrust belt below the edge of a dying glacier in the Tropical Andes","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-11 18:02:04","doi":"10.21203/rs.3.rs-9044279/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-25T15:51:20+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-24T19:56:26+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-19T14:07:27+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"188728282508262858848025995639333537687","date":"2026-03-07T17:42:38+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"310041470158957809160480833895134044038","date":"2026-03-06T13:47:33+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-06T12:53:12+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-06T10:30:12+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-06T10:23:21+00:00","index":"","fulltext":""},{"type":"submitted","content":"Alpine Botany","date":"2026-03-05T22:00:20+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"alpine-botany","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"albo","sideBox":"Learn more about [Alpine Botany](http://link.springer.com/journal/35)","snPcode":"35","submissionUrl":"https://www.editorialmanager.com/albo/default2.aspx","title":"Alpine Botany","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"1a57fffb-25cc-467d-874f-3c35e0b86039","owner":[],"postedDate":"March 11th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-11T08:24:07+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-11 18:02:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9044279","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9044279","identity":"rs-9044279","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}